It is known practice to dye keratin fibers, and in particular human hair, with dye compositions containing oxidation dye precursors, which are generally known as oxidation bases, such as ortho- or para-phenylenediamines, ortho- or para-aminophenols and heterocyclic compounds. These oxidation bases are colorless or weakly colored compounds, which, when combined with oxidizing products, give rise to colored compounds by a process of oxidative condensation.
It is also known that the shades obtained with these oxidation bases may be varied by combining them with couplers or coloration modifiers, the latter agents being chosen especially from aromatic meta-diamines, meta-aminophenols, meta-diphenols and certain heterocyclic compounds such as indole compounds.
The variety of molecules used as oxidation bases and couplers allows a wide range of colors to be obtained.
This process of oxidation dyeing consists in applying to the keratin fibers oxidation bases or a mixture of oxidation bases and of couplers with an oxidizing agent, for example aqueous hydrogen peroxide solution, leaving the application on the fibers, and then rinsing the fibers. The colorations resulting therefrom are permanent, strong and fast with respect to external agents, especially light, bad weather, washing, perspiration and rubbing. Generally applied at basic pH, dyeing and simultaneous lightening of the fiber may be obtained, which is reflected in practice by the possibility of obtaining a final coloration that is lighter than the original color. In addition, lightening of the fiber may have the advantageous effect of producing a unified color in the case of gray hair, and, in the case of naturally pigmented hair, of bringing out the color, i.e. of making it more visible.
It is also known practice to dye keratin fibers by direct dyeing. The process conventionally used in direct dyeing consists in applying to the keratin fibers direct dyes, which are colored and coloring molecules that have affinity for the fibers, leaving the dyes on the fibers, and then rinsing the fibers.
It is known practice, for example, to use direct dyes belonging to the nitrobenzene, anthraquinone, nitropyridine, azo, indoamine, azine or triarylmethane class.
The colorations resulting therefrom are particularly chromatic colorations, that are temporary or semi-permanent since the nature of the interactions binding the direct dyes to the keratin fiber, and their desorption from the surface and/or the core of the fiber are responsible for their poor dyeing power and their poor resistance to washing or to perspiration. These direct dyes are also generally light-sensitive due to the poor resistance of the chromophore with respect to photochemical attack, leading over time to fading of the coloration of the hair. In addition, their light sensitivity is dependent on their uniform distribution or distribution as aggregates in the keratin fiber.
It is known practice to use direct dyes in combination with oxidizing agents. However, direct dyes are generally sensitive to the action of oxidizing agents such as aqueous hydrogen peroxide solution, and reducing agents such as sodium bisulfite, which makes it generally difficult to use them in compositions for lightening direct dyeing based on aqueous hydrogen peroxide solution and based on a basifying agent or in oxidation dye compositions in combination with precursors such as oxidation bases or couplers.
For example, it has been proposed in patent applications FR-1 584 965 and JP-062 711 435 to dye the hair with dye compositions based on nitro direct dyes and/or dispersed azo dyes and on ammoniacal aqueous hydrogen peroxide solution, by applying to the hair a mixture of said dyes and of said oxidizing agent, prepared just before use. However, the colorations obtained are found to have insufficient resistance and disappear on shampooing, making the lightening of the hair fiber show through. Such a coloration becomes unattractive by changing over time.
It has also been proposed in patent applications JP-53 95693 and JP-55 022 638 to dye the hair with compositions based on cationic direct dyes of oxazine type and on ammoniacal aqueous hydrogen peroxide solution, by applying to the hair ammoniacal aqueous hydrogen peroxide solution in a first step, followed by a composition based on the oxazine direct dye in a second step. This coloration is unsatisfactory because it requires a process that is made too slow by the leave-in times of the two successive steps. If, besides that, an extemporaneous mixture of the oxazine direct dye with ammoniacal aqueous hydrogen peroxide solution is applied to the hair, the hair fiber is not colored or at most, a virtually nonexistent coloration is obtained.
More recently, patent application FR 2 741 798 has disclosed dye compositions containing direct dyes comprising at least one quaternized nitrogen atom of the azo or azomethine type, said compositions being for extemporaneous mixing at basic pH with an oxidizing composition. These compositions make it possible to obtain uniform, resistant and bright colorations with glints. However, they do not allow keratin fibers to be dyed as strongly as with oxidation dye compositions.
There is thus a real need to find chromatic direct dyes that allow keratin fibers to be dyed as strongly as with oxidation dyes, which are just as stable as oxidation dyes to light, which are also fast with respect to bad weather, washing and perspiration, and which are also stable enough in the presence of oxidizing and reducing agents to be able simultaneously to obtain lightening of the fiber either by using lightening direct compositions containing them, or by using oxidation dye compositions containing them. There is also a real need to find direct dyes that allow keratin fibers to be dyed to obtain a very wide range of colors, in particular very chromatic colors, not forgetting the “fundamental” shades, for instance, blacks and browns.